Electric Pump

ABSTRACT

An electric pump includes a first housing member, a second housing member, and a partition. The first housing member includes a first support surface and a first seal surface. The second housing member includes a second support surface and a second seal surface. The partition is directly held between the first support surface and the second support surface to form a pump chamber with the first housing member and to form a motor chamber with the second housing member. The motor chamber houses a motor that includes a stator and a rotor. The pump chamber houses an impeller. The partition supports a bearing for holding a rotation shaft coupled to the rotor and the impeller. The first seal surface and the second seal surface directly hold a seal member therebetween.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Japanese patent application serialnumber 2018-171460, filed Sep. 13, 2018, which is hereby incorporatedherein by reference in its entirety for all purposes.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

BACKGROUND

This disclosure relates to electric pumps.

Some electric pumps include a pump-side cover and a motor-side cover.The pump-side cover and the motor-side cover are coupled to each otherto form an interior space that is divided by a partition plate into apump chamber and a motor chamber. The pump chamber houses an impellertherein. The motor chamber houses a stator and a rotor therein. Theimpeller is coupled to the rotor via a rotation shaft that is supportedby a bearing. The bearing is fitted in a through hole formed in thepartition plate.

Two O-rings may be provided at joint portions between the pump-sidecover and the motor-side cover. One of the O-rings is disposed betweenthe pump-side cover and the partition plate. The other O-ring isdisposed between the motor-side cover and the partition plate.

BRIEF SUMMARY

In one aspect of this disclosure, an electric pump includes a firsthousing member, a second housing member and a partition. The firsthousing member includes a first support surface and a first sealsurface. The second housing member includes a second support surface anda second seal surface. The partition is directly held between the firstsupport surface and the second support surface to form a pump chamberwith the first housing member and to form a motor chamber with thesecond housing. The motor chamber houses therein a motor including astator and a rotor. The pump chamber houses an impeller therein. Thepartition supports a bearing for holding a rotation shaft that iscoupled with the rotor and the impeller. The first seal surface and thesecond seal surface directly hold a seal member therebetween.

According to this aspect, the seal member directly held between thefirst seal surface and the second seal surface, and the partition isheld between the first support surface and the second support surface.Thus, the first housing member and the second housing member can stablysupport the partition plate without being substantially influenced bythe seal member. Accordingly, the impeller supported by the partitionvia the bearing and the rotation shaft can be stabilized at a desirableposition. Therefore, vibration generated by rotation of the rotor can bereduced so as to suppress pulsations in discharge pressure of theelectric pump.

Other objects, features and advantage of the present teaching will bereadily understood after reading the following detailed descriptiontogether with the accompanying drawings and the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

For a detailed description of the preferred embodiments of the presentteaching, reference will now be made to the accompanying drawings.

FIG. 1 is a perspective view of an electric pump according to a firstembodiment.

FIG. 2 is a side view of the electric pump of FIG. 1.

FIG. 3 is a top view of the electric pump of FIG. 1.

FIG. 4 is a schematic cross-sectional view of the electric pump of FIG.1 taken along section IV-IV of FIG. 3.

FIG. 5 is an enlarged partial cross-sectional view of the electric pumpof FIG. 1 illustrating region V of FIG. 4.

FIG. 6 is a cross-sectional view of the electric pump of FIG. 1 takenalong section VI-VI of FIG. 4.

FIG. 7 is a schematic cross-sectional view of an electric pump accordingto a second embodiment.

FIG. 8 is a schematic cross-sectional view of an electric pump accordingto a third embodiment.

FIG. 9 is a schematic cross-sectional view of an electric pump accordingto a fourth embodiment.

FIG. 10 is a cross-sectional view of the electric pump of FIG. 9 takenalong section X-X of FIG. 9.

FIG. 11 is a cross-sectional view of the electric pump of FIG. 9 takenalong section XI-XI of FIG. 10.

FIG. 12 is a schematic cross-sectional view of an electric pumpaccording to a fifth embodiment.

FIG. 13 is a schematic cross-sectional view of an electric pumpaccording to a sixth embodiment.

FIG. 14 is an enlarged partial cross-sectional view of the electric pumpof FIG. 13 illustrating region XIV of FIG. 13.

FIG. 15 is a schematic cross-sectional view of an electric pumpaccording to seventh embodiment.

DETAILED DESCRIPTION

The following discussion is directed to various exemplary embodiments.However, one skilled in the art will understand that the examplesdisclosed herein have broad application, and that the discussion of anyembodiment is meant only to be exemplary of that embodiment, and notintended to suggest that the scope of the disclosure, including theclaims, is limited to that embodiment.

Certain terms are used throughout the following description and claimsto refer to particular features or components. As one skilled in the artwill appreciate, different people may refer to the same feature orcomponent by different names. This document does not intend todistinguish between components or features that differ in name but notfunction. The drawing figures are not necessarily to scale. Certainfeatures and components herein may be shown exaggerated in scale or insomewhat schematic form and some details of conventional elements maynot be shown in interest of clarity and conciseness.

In the following discussion and in the claims, the terms “including” and“comprising” are used in an open-ended fashion, and thus should beinterpreted to mean “including, but not limited to . . . .” Also, theterm “couple” or “couples” is intended to mean either an indirect ordirect connection. Thus, if a first device couples to a second device,that connection may be through a direct connection, or through anindirect connection via other devices, components, and connections.

Each of the additional features and teachings disclosed above and belowmay be utilized separately or in conjunction with other features andteachings to provide improved electric pumps. Representative examples ofthe present teachings, which examples utilized many of these additionalfeatures and teachings both separately and in conjunction with oneanother, will now be described in detail with reference to the attacheddrawings. This detailed description is merely intended to teach a personskilled in the art further details for practicing preferred aspects ofthe present teachings and is not intended to limit the scope of theclaimed subject-matter. Only the claims define the scope of the claimedsubject-matter. Therefore, combinations of features and steps disclosedin the following detailed description may not be necessary to practicethe claimed subject-matter in the broadest sense, and are instead taughtmerely to particularly describe representative examples of the presentteachings. Moreover, various features of the representative examples andthe dependent claims may be combined in ways that are not specificallyenumerated in order to provide additional useful embodiments of thepresent teachings.

In conventional electric motors as described above, it is very difficultif not impossible to completely eliminate rotational unbalance of therotor. Accordingly, when the rotor is rotated at high speed, therotation shaft vibrates due to the rotational unbalance of the rotor.This vibration is transmitted to the impeller, thereby resulting in thegeneration of undesirable pulses in the discharge pressure of theelectric pump. Therefore, there has been a need for improved electricpumps.

A first embodiment of the present disclosure will be described withreference to FIGS. 1 to 6. An electric pump according to the firstembodiment is a purge pump 1 that is incorporated in an evaporativeemission system of a vehicle equipped with an internal combustionengine, such as in an automobile. In each drawing, an arrow F defines afrontward direction of the purge pump 1, and an arrow B defines arearward direction thereof.

As shown in FIG. 4, the purge pump 1 includes an impeller 20 and abrushless motor 45. The impeller 20 is coupled to a rotation shaft 41 ofthe brushless motor 45. The brushless motor 45 includes a rotor 40 and astator 50. The rotor 40 is composed of magnetic members, such aspermanent magnets. The stator 50 includes a stator core 51 and statorcoils 52.

The brushless motor 45 and the impeller 20 are covered with a frontcover 11 and a stator body 12, such that the brushless motor 45 and theimpeller 20 are housed in an interior space formed by the front cover 11and the stator body 12. That is, each of the front cover 11 and thestator body 12 serves as a housing member forming the interior space forthe impeller 20 and the brushless motor 45. The interior space definedby the front cover 11 and the stator body 12 is divided by a partitionplate 30 into a front-side space and a rear-side space. The front-sidespace houses the impeller 20 therein and is referred to herein as “pumpchamber” The rear-side space houses the stator 50 and the rotor 40therein and is referred to herein as “motor chamber” The stator body 12may be made from a resin material by insert molding to integrallyinclude a molded part 53 integrated with the stator core 51 and thestator coils 52. That is, a part of the stator body 12 serves as thehousing member, and another part of the stator body 12, for example themolded part 53, corresponds to a part of the stator 50.

As shown in FIGS. 1 to 4, in this embodiment, the front cover 11 has astepped hollow cylindrical shape with a front plate narrowing a frontopening thereof and may be made from a resin material. The front cover11 includes an inlet port 11 a and an outlet port 11 b. The inlet port11 a extends frontward from the front plate of the front cover 11, suchthat the inlet port 11 a is coaxially aligned with the impeller 20. Theoutlet port 11 b extends outward from an outer circumference of thefront cover 11, along a plane oriented perpendicular to the axis of theinlet port 11 a. More specifically, the outlet port 11 b extends in thetangential direction from the outer periphery of the impeller 20. Thus,when the impeller 20 is rotated, the purge pump 1 suctions fuel vaporfrom the evaporative emission system (not shown) via the inlet port 11 aand then discharges it from the outlet port 11 b for supplying the fuelvapor to the internal combustion engine (not shown).

The partition plate 30 may be made from a metal material exhibiting heatconductivity and electric conductivity, and includes a bearing supportpart 31, an outer pipe part 32, and an elastic part 33. The outer pipepart 32 has a hollow cylindrical shape and is fitted within the hollowcylindrical portion of the front cover 11 surrounding the stator 50 in aradial direction perpendicular to the rotation shaft 41. The bearingsupport part 31 has a hollow cylindrical shape. The elastic part 33 hasan annular plate shape extending radially from a front end of thebearing support part 31 to a front end of the outer pipe part 32. Thebearing support part 31 receives bearings 42 therein and supports theouter circumferences of the bearings 42. The bearings 42 are disposedbetween the impeller 20 and the rotor 40 in the front-rear direction androtatably support the rotation shaft 41.

The bearing support part 31 is coupled to the outer pipe part 32 via theelastic part 33. The elastic part 33 is configured to be elasticallydeformed when vibrations are transmitted from the rotation shaft 41 tothe elastic part 33 via the bearing support part 31. More specifically,the elastic part 33 has a shape, for instance a relatively thin flatshape, which more easily deforms compared with the bearing support part31 and the outer pipe part 32. That is, the elastic part 33 has abending rigidity that is less than that of the bearing support part 31and the outer pipe part 32. Because the elastic part 33 is shaped andconfigured to achieve the low bending rigidity, complicated structuresof the partition plate 30 can be avoided.

Due to the foregoing configuration, when the heat generated by thebearings 42 is transmitted to the elastic part 33 via the bearingsupport part 31, the heat is transmitted from the elastic part 33 to thefluid being moved by the impeller 20. In addition, the outer pipe part32 can reduce and/or prevent leakage of noise (e.g., acoustic waves)emitted from the brushless motor 45, and more specifically the statorcoils 52. Further, when vibrations of the rotation shaft 41 aretransmitted to the elastic part 33, the elastic part 33 is elasticallydeformed so as to absorb and thereby reduce the vibrational energy.Thus, pulsations in the discharge pressure of the purge pump 1, whichare caused by vibrations of the rotation shaft 41, can be reduced.Meanwhile, the partition plate 30 has a high bending rigidity part nearthe outer pipe part 32 and in rear of a volute part 21 radially outsidethe impeller 20. Thus, even if the fluid pressure in the volute part 21becomes high, the amount of deflection of the partition plate 30 will berelatively small. Accordingly, the distance between the impeller 20 andthe partition plate 30 can be kept at nearly a constant value, therebyfurther reducing generation of the pulsations in the discharge pressureof the purge pump 1.

The partition plate 30 includes a flange part 30 a extending radiallyoutward from a rear end of the outer pipe part 32. The front cover 11also include a flange part 11 c extending radially outward from a rearend of the cylindrical portion of the front cover 11 and bendingrearward. The flange part 30 a is held between an inner circumference ofthe flange part 11 c of the front cover 11 and a front surface of aflange part 12 a formed at an outer periphery of the stator body 12.

As shown in FIG. 5, the front cover 11 includes a concave part 11 drecessed from an inner circumference thereof. The concave part 11 dincludes a first support surface 11 e facing rearward and a firstsealing surface 11 f facing radially inward. As shown in FIG. 4, thestator body 12 includes a convex part 12 b projecting forward from thefront surface of the flange part 12 a. As shown in FIG. 5, the convexpart 12 b includes a second support surface 12 c facing forward and asecond sealing surface 12 d facing radially outward. The convex part 12b of the stator body 12 is disposed to face the concave part 11 d suchthat the first support surface 11 e and the second support surface 12 cface each other, and further, such that the first sealing surface 11 fand the second sealing surfaces 12 d face each other. The concave part11 d and the convex part 12 b define a space 13 including a bent part 13a that essentially divides the first support surface 11 e and the firstsealing surface 11 f. The bent part 13 a also essentially divides thesecond support surface 12 c from the second sealing surface 12 d. Thefirst support surface 11 e and the second support surface 12 c directlysupport the flange part 30 a of the partition plate 30 therebetween,such that a leading edge of the flange part 30 a is disposed in the bentpart 13 a. Meanwhile, the first sealing surface 11 f and the secondsealing surface 12 d directly support an O-ring 71 therebetween. TheO-ring 71 functions as a sealing member to seal the space 13 between thefront cover 11 and the stator body 12.

As described above, the convex part 12 b and the concave part 11 dsupport the flange part 30 a of the partition plate 30 and hold theO-ring 71. However, these components are being supported and held atpositions different from each other. Thus, the partition plate 30supporting the bearings 42 is stably supported and held between thesupport surfaces 11 e, 12 c without being influenced by the O-ring 71.Thus, the impeller 20 supported by the partition plate 30 via thebearing 42 can be stabilized at a predetermined position. Further, thepartition plate 30 can decrease vibrations, which are generated byrotation of the rotor 40, of the rotation shaft 41 so as to reduce thepulsations in the discharge pressure of the purge pump 1.

The O-ring 71 is held between the front cover 11 and the stator body 12.The partition plate 30 is disposed in a sealed space formed by the frontcover 11, the stator body 12, and the O-ring 71. Thus, both the pumpchamber and the motor chamber can be sealed by a single O-ring 71.Further, due to the simple configuration of the space 13, support of thepartition plate 30 and sealing by the O-ring 71 can be independent ofeach other.

As shown in FIG. 6, in this embodiment, the stator 50 has six poles.More specifically, three of the stator coils 52 are assigned with theU-phase, V-phase, and W-phase of the three-phase current that is appliedfrom a driving circuit (not shown). The other three stator coils 62 areconnected in series to the U-phase, V-phase, and W-phase stator coils62, respectively. The stator coils 62 are arranged in thecircumferential direction. The molded part 53 of the stator body 12integrally couples the stator core 51 with the stator coils 52, so as tomaintain a positional relationship between the stator core 51 and thestator coils 52. The rotor 40 is rotatably disposed at a center of thecircumferentially arranged stator coils 52. The stator body 12integrally includes spacers 12 f for maintaining separation of thestator core 51 and the outer pipe part 32. The spacers 12 f areuniformly circumferentially spaced and are disposed outside the statorcore 51 in the radial direction perpendicular to the axis of therotation shaft 41. Due to this configuration, circumferentially spacedcurved spaces 12 g are formed between the stator core 51 and the outerpipe part 32 such that the stator core 51 is exposed to the curvedspaces 12 g.

As shown in FIG. 4, the flange part 30 a of the partition plate 30 isheld between the flange part 11 c of the front cover 11 and the flangepart 12 a of the stator body 12. The stator body 12 includes aprojecting strip 12 e protruding rearward from a rear surface thereof.The rear side of the stator body 12 is provided with a rear cover 81that functions as a housing member. The rear cover 81 is made of anelectrically conductive material and has a hollow shape having anopening part facing forward. The rear cover 81 includes a groove 81 a atan edge of the opening part. The projecting strip 12 e of the statorbody 12 is loosely fitted in the groove 81 e of the rear cover 81. Thegap between the projecting strip 12 e and the groove 81 e is filled witha seal member 72 formed by injecting a liquid seal agent into the gapand then hardening the agent. Here, the stator body 12 integrallyincludes a connector 91 having a substantial hollow rectangular columnshape. The connector 91 protrudes rearward at a rear portion of thestator body 12 such that an interior space of the connector 91 extendsradially outward. The projecting strip 12 e extends along an outersurface of the connector 91 at a rearward position. The seal member 72also seals a gap formed between the connector 91 and the rear cover 81.

As shown in FIG. 3, four clamps 92 are attached to an outercircumference of the purge pump 1. As shown in FIG. 4, the clamps 92engage with a front surface of the flange part 11 c of the front cover11 and a rear surface of a flange part 81 b of the rear cover 81, so asto fixably secure the front cover 11 and the rear cover 81 to eachother.

In an assembly process, the impeller 20 and the rotor 40 are attached tothe partition plate 30 by the rotation shaft 41 and the bearings 42.They are then inserted into the front cover 11 from the rear. Next, thestator body 12 and the rear cover 81 are attached to the front cover 11from the rear. The assembly of these components of the purge pump 1carried out in one direction, e.g. in the forward direction, simplifiesand eases the assembly process, thereby offering the potential toenhance productivity.

A circuit board 60 is fixed to the rear surface of the stator body 12and is covered by the rear cover 81. The circuit board 60 has a plateshape extending in the radial direction and is within the outercircumference of the outer pipe part 32 of the partition plate 30 from aplan view along the axial direction. The circuit board 60 includescircuit elements (not shown), such as an integrated circuit (IC) chip,on a front or rear surface thereof such that the circuit elements forman electric circuit of the circuit board 60. The circuit board 60 isprovided with coil terminals 61, a power terminal 62, and a groundingterminal 63 that extend forward from the circuit board 60 and penetratethe circuit board 60 rearward to be connected with the electric circuitof the circuit board 60. The circuit board 60 may be integrated with thestator body 12.

The coil terminals 61 are electrically coupled to the stator coils 52.The grounding terminal 63 contacts an inward surface of the outer pipepart 32 of the partition plate 30 and is connected with the rear cover81. The grounding terminal 63 is also electrically coupled to anexternal grounding terminal (not shown) housed in the connector 91. Thepower terminal 62 supplies electrical power to the electric circuit ofthe circuit board 60. In this embodiment, the power terminal 62 extendsfrom the circuit board 60 and into the connector 91 and is configured tobe connected to an external power source to serve as a “connectorterminal.” The connector 91 may be separated formed from the stator body12.

Because the circuit elements of the circuit board 60 are rearward of thepartition plate 30 and are positioned within the radial periphery of themotor chamber defined by the outer pipe part 32 of the partition plate30, acoustic waves and vibrations emitted forward from the circuit board60 and the stator coils 52 can be absorbed by the partition plate 30. Inaddition, the rear side of the circuit board 60 is covered with the rearcover 81, so that acoustic waves and vibrations emitted rearward fromthe circuit board 60 and the stator coils 52 can be absorbed by the rearcover 81.

A second embodiment will be described. The second embodiment correspondsto the first embodiment with some differences relating to positions ofthe coil terminals 61. Thus, while some of the differences will bedescribed in greater detail below, similar configurations will not bedescribed in the interest of conciseness.

As shown in FIG. 7, each coil terminal 61 of the second embodimentextends forward from the circuit board 60 and penetrates the stator body12. The front portion of the coil terminals 61 are each disposed in thecurved spaces 12 g formed radially outside the stator core 51. The frontend of each coil terminal 61 is connected to the corresponding frontside of the stator coil 52.

In the second embodiment, the stator coils 52 are connected with theelectric circuit of the circuit board 60 via the coil terminals 61disposed radially outside the stator coils 52. Each coil terminal 61 isconnected to the corresponding stator coil 52 via a side of the coilterminal 61 further from the circuit board 60. Accordingly, the coilterminals 61 are not disposed between the stator coils 52 and thecircuit board 60. Therefore, the circuit board 60 can be disposed nearerthe stator coils 52, reducing the size of the purge pump 1 in the axialdirection of the rotation shaft 41.

Each coil terminal 61 is disposed radially outside the stator 50 andpartially overlaps the stator 50 in the radial direction of the rotationshaft 41. For instance, a part of each coil terminal 61 is in a spaceradially outside of the stator 50 in the curved spaces 12 g. Thus, theaxial size of the purge pump 1 is not increased by the coil terminals61. In addition, it is not necessary to provide additional spaces forthe coil terminals 61, so that an increase in the radial size of thepurge pump 1 can be avoided.

Further, the coil terminals 61 receive heat from the stator coils 52 andradiate the heat toward the outer pipe part 32 of the partition plate30. Thus, the heat of the stator coils 52 is radiated to the outside viathe outer pipe part 32 of the partition plate 30, thereby offering thepotential to reduce thermal damage to the stator 50.

A third embodiment will be described. The third embodiment correspondsto the first embodiment with some differences. Thus, while some of thedifferences will be described in greater detail below, similarconfigurations will not be described in the interest of conciseness. Forinstance, the purge pump 1 of the third embodiment includes a rear cover82 and a seal member 73, instead of the rear cover 81 and the O-ring 71of the first embodiment.

As shown in FIG. 8, the rear cover 82 includes a flange part 82 bextending forward from a radially outer periphery of the rear cover 82.The flange part 82 b extends forward so as to be radially outside theflange part 11 c of the front cover 11, e.g., by surrounding an outercircumference of the flange part 11 c of the front cover 11. The flangepart 82 b of the rear cover 82 may also be positioned so as to overlapthe flange part 12 a of the stator body 12. At least a majority of theportion of the coil terminal 61 is not overlapped by the outer pipe part32 in the radial direction.

The front cover 11 is coupled to the rear cover 82 by the clamps 92 in astate where the flange part 12 a of the stator body 12 is held betweenthe front cover 11 and the rear cover 82. However, it may be difficultto secure clamps 92 attached to a position where the flange part 82 b ofthe rear cover 82 is positioned radially outside the flange part 11 c ofthe front cover 11. So, the flange part 82 b may have some cut portions,e.g. notches, such that the clamps 92 can engage with the flange part 11c of the front cover 11 and can engage an outer periphery 82 c of abottom portion of the rear cover 82 at the cut portions.

The flange part 12 a of the stator body 12 includes a convex portionprotruding from a front surface thereof. The flange part 11 c of thefront cover 11 includes a concave portion recessed from a rear surfacethereof. The convex portion of the flange part 12 a is loosely fitted inthe concave portion of the flange part 11 c. A gap between the concaveportion of the flange part 11 c and the convex portion of the flangepart 12 a is filled with a seal member 73 formed by injecting a liquidsealing agent into the gap and then hardening the agent. Similarly, theseal member 72 is provided between the flange part 12 a of the statorbody 12 and the outer periphery 82 c of the bottom portion of the rearcover 82.

In accordance with the third embodiment, the rear opening of the outerpipe part 32 of the partition plate 30 is covered with the rear cover82. That is, the outer pipe part 32 of the partition plate 30 openstoward an interior space of the rear cover 82. Thus, when acoustic wavesand vibrations are emitted by the stator 50 and leak from the rearopening of the outer pipe part 32, the rear cover 82 can prevent leakageof the acoustic waves and vibrations to the outside. Further, acousticwaves and vibrations emitted by the coil terminals 61 in a directionperpendicular to the coil terminals 61 can be absorbed by the flangepart 82 b of the rear cover 82.

A fourth embodiment will be described. The fourth embodiment correspondsto the first embodiment with some differences. Thus, while some of thedifferences will be described in greater detail below, similarconfigurations will not be described in the interest of conciseness. Forexample, the elastic part 33 of the fourth embodiment includes supportparts 33 a.

As shown in FIGS. 9 and 10, the elastic part 33 includes four supportparts 33 a arranged circumferentially between the bearing support part31 and the outer pipe part 32. Each support part 33 a may be formed tobe elastically deformable by cutting a part of a front plate portion ofthe partition plate 30 and bending the part toward the motor chamber. Asshown in FIG. 9, a leading edge 33 b of each support part 33 a contactsa front surface of the stator body 12. As shown in FIGS. 10 and 11, eachsupport part 33 a includes a guide surface 33 c extending in a flowdirection of a fluid forced by the impeller 20 along the support part 33a of the partition plate 30, which is shown by dashed arrows in FIGS. 10and 11. Accordingly, the leading edges 33 b are positioned on adownstream side of the fluid flow. As a result of cutting and bendingthe partition plate 30 to form the support parts 33 a, the partitionplate 30 includes an opening 33 d in front of the support parts 33 a.

As shown in FIGS. 10 and 11, each support part 33 a actually extends ina circumferential direction about the axis of the rotation shaft 41 andbends rearward. In FIG. 9, solid arrows show a flow of the fluid, e.g.air containing fuel vapor, which is suctioned via the inlet port 11 aand then is discharged from the outlet port 11 b by the impeller 20.Meanwhile, dashed arrows show a flow of a part of the fluid, which flowsinto the motor chamber through the openings 33 d.

In accordance with the fourth embodiment, the leading edges 33 b of thesupport parts 33 a contact the front surface of the molded body 53 ofthe stator body 12. So, the partition plate 30 is biased forward due tothe elastic force of the support parts 33 a, when the flange part 30 aof the partition plate 30 is engaged with the flange part 11 c of thefront cover 11. Thus, the partition plate 30 can be positioned at apredetermined position with respect to the stator 50. As a result, theimpeller 20 supported by the partition plate 30 via the bearings 42 andthe rotation shaft 41 can be positioned at the predetermined positionwith respect to the stator 50. In addition, when vibrations aretransmitted from the rotation shaft 41 to the support parts 33 a, thesupport parts 33 a elastically deform so as to absorb the vibrationalenergy. Further, because the fluid flows from the pump chamber into themotor chamber through the openings 33 d of the partition plate 30, thepartition plate 30 and components of the brushless motor 45 can becooled. For example, the fluid flow includes a first flow passingradially outside the bearings 42 to a space between the rotor 40 and thestator body 12 and a second flow toward the curved spaces 12 g. Thus,the bearings 42, the stator body 50 and the partition plate 30 can beefficiently cooled.

The guide surface 33 c of each support part 33 a extends along thedirection of the fluid flow generated by the impeller 20. Thus, thefluid flows smoothly along each guide surface 33 c from the pump chamberinto the motor chamber through the openings 33 d, so that the motor canbe efficiently cooled by the fluid. Further, the partition plate 30includes four support parts 33 a and is supported on the stator body 12by the support parts 33 a, each radially positioned outside the bearings42. Thus, the partition plate 30 can be stably supported on the statorbody 12. To ensure the stable support of the partition plate 30 on thestator body 12, the number of the support parts 33 a is preferably equalto or greater than three.

A fifth embodiment will be described. The fifth embodiment correspondsto the fourth embodiment with some differences. Thus, while some of thedifferences will be described in greater detail below, similarconfigurations will not be described in the interest of conciseness. Forexample, in the fifth embodiment, one of the bearings 42 is disposedfrontward of the rotor 40, and the other is disposed rearward of therotor 40.

As shown in FIG. 12, the bearings 42 support the rotation shaft 41 onboth sides of the rotor 40. The rear-side bearing 42 is directly affixedto the stator body 12. Thus, the rotation shaft 41 is supported so as tostabilize the position of the impeller 20. As a result, vibration of therotation shaft 41 can be suppressed, thereby decreasing pulsations inthe discharge pressure of the purge pump 1.

A sixth embodiment will be described. The sixth embodiment correspondsto the fourth embodiment with some differences. Thus, while some of thedifferences will be described in greater detail below, similarconfigurations will not be described in the interest of conciseness. Forexample, the elastic part 33 of the sixth embodiment includes supportparts 33 e, instead of the support parts 33 a of the fourth embodiment.

As shown in FIGS. 13 and 14, the elastic part 33 includes the supportparts 33 e near the outer pipe part 32. Each support part 33 e may havealmost the same shape as each support part 33 a of the fourthembodiment. However, the leading edges 33 f of the support parts 33 econtact corresponding front surfaces of the spacers 12 f Each supportpart 33 e may actually be formed by cutting a part of the partitionplate 30 along an inner periphery of the outer pipe part 32 and bendingthe part rearward. Thus, each support part 33 e extends in thecircumferential direction about the axis of the rotation shaft 41 andslopes rearward, similar to the support parts 33 a shown in FIGS. 10 and11. The partition plate 30 includes openings 33 g in front of thesupport parts 33 e. Each opening 33 g is formed by cutting and bendingrearward the corresponding support part 33 e.

In accordance with the sixth embodiment, the openings 33 g are disposedbackward of the volute part 21 and located radially outside the impeller20. Thus, the fluid easily flows from the volute part 21 into the motorchamber through the openings 33 g, so as to cool the components of thebrushless motor 45 more efficiently.

A seventh embodiment will be described. The seventh embodimentcorresponds to the fifth embodiment with some differences. Thus, whilesome of the differences will be described in greater detail below,similar configurations will not be described in the interest ofconciseness. For example, in the seventh embodiment, the bearing supportpart 31 of the partition plate 30 is configured to house the rotor 40and the bearings 42 therein. The partition plate 30 is made from anonmagnetic material.

As shown in FIG. 15, the bearing support part 31 has a hollowcylindrical shape with a closed rear end such that the bearings 42 andthe rotor 40 are housed therein. The bearing support part 31 supportsthe outer circumferences of the bearings 42 and is disposed along aninner circumference of the stator 50. Thus, the bearing support part 31can transmit heat from the bearings 42 and the stator 50 to the outerpipe part 32, thereby radiating heat from the outer pipe part 32 towardthe outside of the purge pump 1.

The present teaching is not limited to the above-described embodimentsand can be modified in various ways while being within the scope of theteaching. For example, the present teaching can be applied to variouspumps instead of the purge pump 1 installed on the vehicle. Variousmotors can be used instead of the brushless motor 45. For example, it ispossible to use a motor including stator coils that arecircumferentially arranged and an annular rotor disposed around thestator coils.

What is claimed is:
 1. An electric pump, comprising: a first housingmember including a first support surface and a first seal surface; asecond housing member including a second support surface and a secondseal surface; a partition directly held between the first supportsurface and the second support surface, the partition, wherein a pumpchamber is disposed between the partition and the first housing memberand a motor chamber is disposed between the partition and the secondhousing member; a motor disposed in the motor chamber and including astator and a rotor; an impeller disposed in the pump chamber; a bearingsupported by the partition; and a rotation shaft supported by thebearing and coupled to the rotor and the impeller, and a seal memberdirectly contacting the first seal surface and the second seal surface.2. The electric pump according to claim 1, wherein: the first supportsurface is closer to the pump chamber than the first seal surface; andthe second support surface is closer to the motor chamber than thesecond seal surface.
 3. The electric pump according to claim 1, wherein:the first housing member includes a concave part; the second housingmember includes a convex part that faces the concave part to form aspace having a bent part therebetween; the first support surface and thefirst seal surface are separated from each other by the bent part; andthe second support surface and the second seal surface are separatedfrom each other by the bent part.
 4. The electric pump according toclaim 1, wherein the partition is made from a metal material andcomprises: a bearing support part directly supporting the bearing; and apipe part housing the stator and the rotor therein.
 5. The elastic pumpaccording to claim 4, wherein: the pipe part includes a first end, thepartition includes an elastic part coupling the bearing support part tothe first end of the pipe part; and the elastic part is configured to beelastically deformed when vibrations are transmitted from the rotationshaft to the elastic part via the bearing support part.
 6. The electricpump according to claim 5, wherein the elastic part of the partition hasa bending rigidity that is less than a bending rigidity of the bearingsupport part and a bending rigidity of the pipe part.
 7. The electricpump according to claim 5, wherein: the pipe part of the partitionincludes a second end positioned opposite to the first end and a flangepart protruding radially outward from the second end; the flange partengages with the first housing member in an axial direction of therotation shaft; and the elastic part comprises at least one support partbeing elastically deformable and contacting the stator in the axialdirection.
 8. The elastic pump according to claim 7, wherein: theelastic part comprises at least one opening; and the at least onesupport part extends from an edge of the at least one opening.
 9. Theelectric pump according to claim 8, wherein the at least one supportpart includes a guide surface extending in a circumferential directionabout an axis of the rotation shaft and forming a flow path from thepump chamber into the motor chamber through the at least one opening.10. The electric pump according to claim 7, wherein the at least onesupport part includes three or more support parts.
 11. The electric pumpaccording to claim 4, further comprising: a circuit board electricallycoupled to the stator and positioned on a side of the second housingmember opposite the motor chamber, wherein a dimension of the circuitboard in a direction perpendicular to an axis of the rotation shaft issmaller than an inner diameter of the pipe part of the partition. 12.The electric pump according to claim 11, further comprising: a pluralityof spacers disposed between the stator and the pipe part of thepartition, wherein the spacers are circumferentially spaced about theaxis of the rotation shaft to form therebetween a plurality ofcircumferentially spaced curved spaces.
 13. The electric pump accordingto claim 12, further comprising: a coil terminal extending through oneof the curved spaces; wherein: the stator includes a plurality ofcircumferentially arranged stator coils; and the coil terminalelectrically connects the circuit board with one of the stator coils.14. The electric pump according to claim 11, further comprising: a rearcover positioned on a side of the circuit board away from the motorchamber, wherein the rear cover is electrically coupled to the partitionand has a dimension larger than the inner diameter of the pipe part ofthe partition in the direction perpendicular to the axis of the rotationshaft.
 15. The electric pump according to claim 4, wherein: the statorincludes an inward facing surface directed to the rotor; and the bearingsupport part is disposed along the inward facing surface of the stator.16. The electric pump according to claim 1, wherein: the first housingmember includes an open end sized and configured to receive theimpeller, the partition, and the motor therethrough and into the firsthousing member; and the open end of the first housing member is closedwith the second housing member.